Arum italicum - how to eradicate

shelley_r(7b NC)November 13, 2004

I've just learned how invasive this plant can be. I'm trying to help someone get rid of the arum that has spread over 5+ acres of a beautiful woodland garden. The garden is mostly native plants so we really want to get rid of this pest. I've been told that all the experts say you just can't eradicate arum and my short research backs that up. Isn't there anything that works? Please help me with this. Thanks for any suggestions and information.

If you're really determined, perhaps the easiest would be a winter (like now) application of roundup to the clumps. You're less likely to hit much else (that's not evergreen) this time of year...and the arum is in full evidence.
It won't be easy..but you said you really wanted to get rid of it.
Alternatively (silly idea maybe), find nurseries in your area that would like to sell arum italicum and invite them in to dig ?
I live out west and don't believe italicum is a rampaging threat here (w/o irrigation). But having seen 5 acres of vinca minor (back farther east), I believe you...

i have dug up my plnt corms many times. apparantly a little bud must survive each time because i keep getting sprouts. i had read not to keep the plants in a wet location. well, it was pretty wet, and the corms were pretty mushy, but they keep coming.

Shelley, you are going to have to get a bigger gun. There should be farmers in your area who use some really potent herbicides. Too many weeds are already resistent to Roundup [glyphosate]. You can get other translocating herbicides, but many may be also restricted-use and will take either a professional or a farmer [with an applicators permit] to help your friend with the Arum problem.

There have only been a few cases of weeds that have become resistant to Roundup, and these are generally in agricultural situations. There is no evidence that such genetic resistance development has taken place in the scenario described in this thread. If there is a lack of efficacy from Roundup on A. italicum, it stems from the natural and inherent ability of this plant to resist its effects. Glyphosate should work, although repeat applications are likely needed, and it should be timed for later in the growing season. 2,4-d products are also reported as effective on this weed.

Well, I've done some research and that with the comments here leads me to believe that you cannot dig it out successfully. As fairy_toadmother says, you'll always miss a little corm. As for stronger poisons than Roundup, that's out, too. This is an important wildflower garden and I can't take any chances that might accidentally destroy another desirable plant.

I'd appreciate any comments on the best method of applying Roundup. Just spraying it on the leaves doesn't seem to work. We cut the foliage off some of the plants and dipped the cut stems in full-strength Roundup. Haven't had a chance to evaluate that method yet, but I'm inclined to continue with it. Should I get the plants as soon as they emerge or wait until they've got some growth first. Cut them off close to the ground or leave the stem as long as possible. Or just nick the leaves so the Roundup can enter the plant better. Ideas?

Roundup is a systemic herbicide and should be applied when the plant is moving energy reserves from leaves to the roots. This varies with the plant, but in the case of Arum it appears to be mid growing season and beyond. Once applied to the leaves and stems, do not cut any foliage. Another addition would be to use an extra surfactant in the spray mix to assure good penetration of the herbicide.

Put some dish soap and fertiliser into your Round-up. The dish soap is a surfactant, which helps the round up get to the leaves themselves, and the fertiliser will cause the plant to suck up the round up. Do this while the plant is moving energy and food from the leaves to the roots....usually mid-season. April

I am a CPA (certified pesticide applicator)(possibly certifiable too :~) I have found the best way to use roundup in a situation like this is to wait until the plants are ready to go dormant and are pulling all the nutrients from the leaves back to the corms. then cut the foliage off near the ground and immediately paint on the straight roundup. it is pulled back to the root system killing the plant. This method has worked wonderfully for me in controlling poison ivy, buckthorn, and several other tough to control weeds.

On another note, I'd be happy to pay shipping for a load of corms, A. italicum is rather rare here and deer (piranha deer that is) won't eat it, and it is not a problem plant in this area. Send me an e-mail if you'd care to share.
Fred

fredsbog says....'then cut the foliage off near the ground and immediately paint on the straight roundup'

Thats a great technique for woodies like buckthorn or poison ivy and is a method that is labeled and widely accepted. But for non woody plants, cutting right before application does not increase but reduces it no matter what state the plant is in, and is not recommended. Read the label-it specifically states to apply on actively growing plants. It's also a waste of money to not get max application and max translocation.
I am also a certified applicator....

Rosa, could you explain why cutting the plant near the ground works for woodies, but not for perennials? I'm not doubting you at all nor the Roundup instructions. I'm just curious and trying to learn why plants behave as they do.

Cutting the Arum near the ground and painting with full-strength Roundup is what I'd planned to do. It seems like the open stems would just suck it up.

It has to do with the arangement of vascular bundles and the tensions they maintain to move water/nutrients, and sugars in the plant.
In grasses and broadleaf forbs these 2 types of vessels are bundled together and move water/nutrients up to the leaves as the other vessels are moving sugars down to the roots. Cutting the leaves at the ground disrupts the flow both ways. Nothing going up also means nothing going down. This is true for Roundup type herbicides known as growth regulators that are moved thru the plants with the sugars and into the roots and storage organs.

In woody vegetation the bundles are seperate and spaced further apart. The ones that transport sugars are on the outside all the way around near the bark. The ones that transport water/nutrients are in the wood, sapwood and heartwood. They work a little more indpendently so to speak. It's why you can tap sugar maples and not disrupt the flow upward or downward. The pressure gradients for upward and downward movement are slightly different
Cutting woody vegetation at the base and applying herbicide still results in the herbicide being sucked into the roots.

While there are some exceptions to this as KAYK mentions I would not recommend that for you or your situation. Companies spend alot of money and time figuring out exactly what works. It's not a guess, its based in science. I would apply as indicated on the label.

To clarify some things:
Roundup is not a growth regulator type herbicide. It works by affecting amino acid synthesis.
There is no water transport in heartwood.

There are labeled uses for Roundup application to non-woody cut stems, for example, knotweed, as I previously mentioned.

Another well known examples is Arundo donax-
TNC website:"Arundo- Cut-stem treatment requires more time and manpower than foliar spraying and requires careful timing. Cut stems must be treated with concentrated herbicide within one to two minutes in order to ensure tissue uptake."

All this being said, for Arum italicum a late season foliar application of Roundup at the label rates, with enough surfactant to ensure foliar penetration would likely be a good method if glyphosate is the choice.

Yes, my mistake, should have said wood and sapwood. Even tho the heartwood is the central core of the xylem it has lost the abliity for transpost due to clogging of the vesels.

And yes Roundup is indeed an amino acid distruptor-sorry, looking at the wrong column.

But, my labels of Roundup do not indicate any instructions for cutting of herbaceous plants before application.

Roundup Pro & Pro Concentrate, Pro Dry...apply to actively growing weeds..allow growth to reccur before treatment
Roudnup WeatherMax...do not treat until weeds have resumed active growth and reached recommended stages
Roundup Original, Original 11, Original Max...reduced control may result when weeds have ben mowed, grazed or cut and have not been allowed to regrow
Roundup UltraDry, Ultra Max, Ultra Max 11...if weeds have been mowed or tilled do not treat until weeds have resumed active growth

What am I missing here??
I'm certainly not debating whether TNC (a great resource btw) has used Roundup in the manner you stated for Arundo. Just whether the product is specifically labeled for such type treatment and can find none! I can't even find any mention of controlling Knotweed on any label..

For novice users, I always recommned following the label first before getting experimental. In most cases this works perfectly well.

You will find Arundo cut stem treatments detailed in the Roundup Pro label, for one.

Aside from the Arum question, it is important to know that not all weed targets need to be listed on a label to be legal targets for a given herbicide. What matters is that the *site* is legal for an application. No herbicide label lists every weed that it is legal to be applied to.

I concur that novice users, and experienced users for that matter, should adhere to the label directions.

I really appreciate all the discussion on the application of Roundup. I have learned a lot. I just want to focus back on one thing, though, which is that the anecodotal evidence is that Roundup applied according to the label directions just does not work with Arum. So, wanting to stick with Roundup rather than use anything stronger, what would be my best bet as to application method? Maybe I can report next year on what seemed to work the best.

True JAYK, is the site that's important.
Just trying to find something indicating treatment type for either knotweed or Arundo as mentioned. Maybe just blind in the am without much coffee, lol!!

Shelly, take JAYK's advice, a late season foliar application of Roundup at the label rates, with enough surfactant to ensure foliar penetration...

Many failures in weed control imho, stem from: using the wrong product, a premixed product on hard to eradicated weeds (these are just not mixed in strong enought concentrations to do the job on really tough weeds), and improper application whether that be the wrong time of year, wrong biological stage of the plant, wrong temperature for maximum efficacy, etc...
There are instructions on the Roundup label for mixing at various strenghts. Stick to the label and don't EXCEED the highest rate listed, and do not forget the surfactant at the rate recommended. It's good use of you money to use it-they are not all that expensive in the scheme of things.

I may be a year late and data short, but here is what we do in Hawaii to kill bananas. To kill diseased ones (from a virus, BBTD) we use straight Roundup and INJECT it into the fleshy banana plants. Mongo syringes can be had from surfboard shops ("resin syringes" which are plastic and safe to carry casually), wallpapering shops ("paste syringes") or horse feed stores (they have lots of sizes). The metal ones are extremely sharp. I dull mine a little with a file.

A week later you can see the huge banana plant fading fast, and it kills all the attached (and assumed infected) siblings.

Thanks for all the good posts - I was looking for whether the Roundup flowed in the center or bark area of woody plants.

I have heard people talk about Arum Italicum as being horribly invasive. Someone gave me some as a gift...Should I plant it in my yard or not, I can't decide! It would be in pretty moist soil, and in partial shade.

Rookie, Arum would thrive in the conditions you describe. I would NOT plant it.

We used a method very similar to what Fred described. We cut the foliage and carefully dipped the stem in full-strength Round-up. Several people thought that the garden had less Arum this year, so I believe that the method worked.

This will be a multi-year project and I might try Ray's suggestion (injecting Round-up) next time.

I am so glad I found this discussion! I was just looking at a full page picture of this plant and thinking how great it would be to own one. I wonder why the plant magazines always tell us all the good things about a plant but not always all the bad.

I don't recommend planting this species. It has invaded both mine and my neighbors' yards and is so difficult to get rid of. I have taken to digging them up whenever I see them. So if anybody really wants them I have thousands. But get them quick, b/c I'm going to try the injecting-round-up idea.

This plant is on NC's watch list A. It is not higher up because the invasive list is based on what has escaped to the forests and natural areas. So far it is only a problem in gardens, really a thug here. I got my first piece from the very garden Shelly is trying to help clean up and am trying to kill mine. Just a few years ago we did not realize how invasive it could be! It is a beautiful plant. Too bad it has such bad habits. Keep working hard, Shelley, and I will join you on one of the Friday workdays! Oh, and remember that RoundUp has gotten some bad press at Cullowhee.

Well, here I am sitting in a garden that has just a few of them, and LOVING IT! I have clay soil, dry shade, and lots of tree roots, so maybe that's why they don't get out of bounds for me. I wish they would spread more, but they seem to stay in small clumps.

Most of you must have nice fluffy soil yours are growing in, so that they spread like mad.

BTW - this is not native to North America; it is an exotic species from Southern and Western Europe that has naturalized in gardens here in the U.S.

Susan

If you like them, try growing them in pots, a buried pot, or buried tub of sorts so the tubers don't multiply outside of a confined environment.

I think they're beautiful, and here they are green all winter in my drab, brown landscape.

These just started springing up in my vegetable patch, and while they're beautiful, I'd rather they stayed away from my tomatoes and basil.
So I'm going to try bringing them in as houseplants. If they survive, that's cool. But given my track record with houseplants, they haven't got much chance! *G*

On a serious note, Susan, you may have just helped me solve my dilemma.

First, I have trouble growing anything (but blackberries and wild morning glories and English ivy) on the north side of my house, because it's too shaded, the soil tends to get dry because of the roof overhang, and because the soil is mostly clay. Maybe I can transplant my (volunteer) Gigaro to that side of the house and let it do its thing there.

But I love your idea of putting them in big pots, where you can enjoy their beauty but keep them from strangling the veggies and flowers.

Don't plant the stuff, don't give it away. It is causing serious problems in natural areas in some parts of the country. All the advice given on eradicating this weed with Round-Up is good, and should work for you. This is a tough plant to get rid of, good luck!

I am concerned that there is a discussion about eradicating an invasive plant and yet people are asking for divisions of it.

DON'T PLANT IT! DON'T TRADE IT! DON'T GROW IT!

The plant may not be listed as invasive where you live right now, it could become listed as more information is collected over time... save yourself the hassle and keep invasive plants out of your landscape, no matter where you live.

Hmmm I don't know. I myself and sad to see one of my clumps go. Especially since I have had these two clumps for twenty+ years and have enjoyed the "hassle". So if you have no intention of maintaining your gardens properly then by no means should you bother with invasives. If however you actually like to work in your gardens then arrum italicums are really not that hard to control. I'm sorry all but I feel specimen cultivation to be just as important as maintaining natives.

This plant is the worst ever. DO NOT PLANT IT!!!!!!!!
I have dug it, injected purple round up into the ground, sprayed it with round up, covered it with black plastic for the entire summer and now...... it is growing through the plastic and spreading into my beds.
I asked at Portland Nursery what I could do- and the horticulturalist said VOODOO.
Funny- but true?
I might just have to move to get away from it.
I have worked so hard on my garden and this plant is invading all of my hard work.
What else can I do?
What other chemicals or techniques can I use?
Please help!

I am in the same boat as you. I bought a house in Woodburn 2 years ago that has most of the backyard covered by Arum Italicum. My thought at the time is that I love to work outside, and I can deal with the stuff. Eesh! what a job!

Last year I sprayed D4 Amine on the Arum and it did kill the foliage, but it returned this year. I have been getting outside nearly every weekend and digging up the corms this year.

I really wish there was an easy way to get rid of this pest. If you find one, please let know:)

!!! I cannot believe my eyes. I bought some plants from a very very well know nursery in 2003.
The clump has hardly expanded. I even collected the seeds
and planted them at the base of the clump a couple years ago.

How can the nurseries sell it? I really like it. Now I have something to worry about.

I don't know how, but I wanted to share that recently on a tour of a public garden that is supposed to be "natural," I saw this plant everywhere! Someone must have donated it years ago, and it has spread far and wide to all corners of this park. The green leaves are lovely, yes, but they will never be able to subdue it, must less control it. Does anyone know if it stops other things from growing up through it? I do know that English ivy, as horrible as it is, does allow some things to grow up through it. I don't want ivy, but at least it does not smother everything...just kills trees and pulls the mortar out of the brick walls. That's not a nice plant, either.

When we moved to this house in 1991, there was a little of this stuff. The berries made my daughter's hands itch which first got my attention. I didn't know what it was then. It has since invaded every bed. Here in Portland, the leaves come out in winter, flowers about July followed by the berry stalks in September. I have tried a lot of sprays and stuff. Diluted round up will kill the leaves if saturated, but still it flowers and proliferates. I have never tried using straight round up concentrate. My neighbor has suggested crossbow(?). Awhile back on this site someone from Hawaii suggested injection of round up. Did that work for anyone?
Since it is in theory actively growing now in midwinter, I am going to try cutting the leaves and dipping the stems in concentrate for a few minutes. It was a little hard to follow the earlier discussion by certified pesticide appliers, but I think that was the recommendation. I also thought about applying PREEN around the base of some of it. I think that is a corn based product that inhibits growth.
May as well experiment this year. I'm done trying to dig it out.

Here is a little organic trick I use with hard to get rid of flora - - 'boiling hot water'. Just hard boil (not simmer) some water and carefully pour it on the plant you want to get rid of. It works wonders on weeds and grasses that can come up between the cracks of your drive or walkway as well. I know that what you want to do is kill it ..and this trick may not do that..but it will keep it away for a long time. To try to kill it ..add a good bit of regular table salt to the water then bring it to a boil. Most plants hate salt and will die.

Thankis, ahughes! I will do that unless I find out that boiling will do the same thing! ;o) Will it? A lot less energy to boil than bake. Except...I DO have a little toaster oven! Nevermind...I'll you the little oven!

ontheteam, I nuked my arum a few days ago. Worked very, very well...until they caught fire! :/ Arum is dead for good, but my microwave will forever smell like burnt arum, I'm afraid.

eagerdrone, I battle morning glories, too. My back neighbor used to hang fishing line and let them climb into my pine tree. This was every year (3) the house sat empty. Now they are everywhere and I can hardly get rid of them all.

Arum Lily is a problem for us here in Northland New Zealand.
As a Biosecurity Officer, working for the Regional Council, I often get asked about such plants. We have found Grazon (picloram and 2,4-D)seems to work, or Metsulfuron methyl, although it takes longer.
I'm running some trials thisseason, so should be able to come back with some good information!
By the way, I've never had any lasting result from glyphosate on any of the arum family, no matter how it has been applied
The Aussies have been fighting it's spread for many yeasrs as well.

This is a great discussion, and the info on how glyphosate (I likely mangled that spelling) works is so valuable I'm going to print it and file it. Thanks to all.
Just for clarification, in which zone does arum italicum start to be a pest? I'm in zone 6, and I want to plant it, but I want to be mindful of this plant's invasive potential. FWIW, here's my two cents on the invasive plant debate: If the plant in question is not known to be a pest in your zone, I don't see any reason not to plant it. Ornamental exotics that behave themselves and are avoided by deer and other critters are always welcome in my garden.

I have been trying to eradicate arum italicum for a few years now. Sometimes I thought I was being successful, but I think I am losing. I have regularly used Round-Up and have also dug them and used a torch. I have decided to dig them as soon as I see them now. No arum plant has been allowed to go to seed here for over three years. They do appear in new places seemingly by immaculate conception, so more places to attack--to dig, burn, glyphosate--anything. I am relentless, but so is this plague. I would not give arum to my worst enemy, for I consider it a plague to the planet. The only suitable place to plant this beautiful plant is in concrete or stainless steel--and then not allow it to go to seed. It can reproduce easily underground and by seeds spread by birds, I believe. FAIR WARNING! I believe it is a plague in any zone!

I got the Plant Delights e-newsletter today and I thought it was odd that it said:

At Open House this winter, I had a couple of folks comment about their arums spreading by runners to other areas of their garden. This is an oft perpetuated garden myth, since arums, like me and my bad knees, have no ability to run. When arums are allowed to set seed, birds can pick up the seed and deposit them anywhere throughout your garden. This is the only way arums can spread. If you get to the point where you have enough arums, simply cut off the flowers or developing seed between the time they flower in early May and the time the seed ripens in July.

I purchased my house south of Portland, Ore., almost two years ago now. I have been using Crossbow (active ingredient: triclopyr + 2,4-D ester) for about a year and a half (once in late spring and once in autumn for anything missed in spring). I just got done applying it again and am ready to get a flamethrower. The arum, along with their patches, seem to be getting smaller but it's migrating into my perennials which makes spraying difficult.

Have just found this thread having googled 'how to kill wild arums'. Having looked at the Wikipedia entry I realise, duh! that I also have several very large spadix in the borders which I have been uprooting, but my Dad asked me to leave one because the birds like it. http://en.wikipedia.org/wiki/Arum_maculatum. When the ground isn't frozen, I'm going to fell the last one and not leave any of the berries around, because it could be the birds spreading the arums after eating the berries. I'm going to keep searching for some sort of alternative way of killing them - there must be something wild lilies hate, eg cigarette ash?!

Lord, it did my heart good to see so many others out there that absolutely are beside themselves trying to get rid of this obnoxious weed. My mother-in-law gave me this plant 45 years ago. I wish she had taken it to the grave with her. I live in rural Oregon and it is always wet. I the guy that said he needed a bigger blow torch.

I too have a huge yard, but this is war. Since we spray the roads with weed killers I'm going to pinch a few gallons for the yard. These things are under bushes, snuggeled up to the roses and have traveled with the compost to all corners of the yard. It is a nightmare.

Hmm. Arum Italicum "Pictum" has been in my zone 6 garden for over 20 years and has not spread to more than a couple of places other than where it was originally planted. Clumps continue to get bigger but it doesn't seem to be reseeding anywhere, not even close to the original plants. However, I will keep an eye on it for seedlings in the woods in the future. As of now there are only 4 plants, two of which I actually planted.

I live in Zone 6 in the northeastern US. I had a landscaper plant about 20 corms several years ago but never got more than a few speckled leaves every January. I thought I had purchased inferior corms, or the clay here was too heavy & dry, so I planned to purchase more this year. However, this chain of posts has made me reconsider. But I really like them so may roll over and try Susanlynne's suggestion and plant them in pots. I'll keep you posted. BTW, I wonder how the originator of this thread from 2003 made out.

The garden where the original poster worked is STILL having volunteers dig out these plants! I have to say we have made some progress, but look how many years it has been...and how many volunteers help out there. The soil in the garden is so good and soft that these plants just send down their roots so deeply that it is hard to get them out. We keep trying.

I have some of these arums that I am trying to get rid of. Got them via the original garden but with other plants. They were lurking in the soil that I took home.

I too have invasive italicum arum and believe me you don't want this stuff, I live in Oregon and bulbs flourish here I also have grape hyacinths that are just about as invasive and these bulb type plants are like the energizer bunny they keep producing and producing. Turn your soil over and you'll see the bulbs all over the place. It is very frustrating. I am going to try the Round up because the stems of the Italicum arum go down a ways in the soil and it is difficult to remove the bulb and if you use a shovel and cut it, you just have two new arums to deal with later. I think I may have contracted this Italicum Arum disease from a local soil company that composts soil from peoples

Has anyone tried a flame weeder on their Arum? I just bought a flame weeder, and so far am impressed with how quickly the weeds die. I thoroughly water the area I am working in, to avoid fires, and I keep my hose handy...

Another idea, dig up what you can, cover with several layers of newspaper and then mulch over that.

Watch out for local soil companies that turn other peoples yard debris into mulch and compost, I think that the bits and pieces of the bulbs left over in their yard debris are what start these invasive plants in our gardens and yards. I didn't have this problem until I bought the local compost for my garden. Also check out the article in this months April/May 2011 edition of Mother Earth news about "Killer Compost".

Since I last wrote in 2009--before I had arum italicum on the run--I was frustrated. I have found a product that will kill it. It is Speedzone. Google this to find local sources. I have almost no arum emerging from the soil. 3 days ago I saw another leaf emerging, so I sprayed some premixed Speedzone (which I now have on hand always). Today the that leaf is bowing toward the ground and will die. Success again! Nothing I have tried in the past, including digging (which seems to spread these invasive plants), burning, Roundup, etc., has worked. Speedzone does!

We bought a house last March that is infected with Arum. Since we have a 16-month-old who loves to put things in his mouth, I have decided it must all go - all parts of the plant are poisonous, and the berries are particularly enticing.

I have noticed something about the lifeway of the plant that may be useful to know. It appears that the "mature" plant does not give off many of the pea-sized corms at the plant base, but instead has "nobby knees" that could become new plants - in other words, they are part of the plant base and don't easily split off if you gently remove the adult plant. It is the JUVENILE plants that are actively corming. They are shallow-rooted in comparison to the adult, and growing in a group. If you disturb a group of juveniles, you will see corms of all sizes (some quite small) go rolling everywhere. My strategy is to gently loosen a clump of juveniles and throw out the clump in one piece. Then, hunker down and pick through the loose dirt - you'll get the majority of them. Be aware that not every corm is round. I've noticed that the plants that are so young they are "single-leaf" do not have corms at all, so you can move a bit faster when working them.

I have seen arum corms attempting to grow from over two feet down in the soil. It is incredibly tenacious. While I do not like chemicals, I may start carefully using Speedzone here and there.

I'm surprised no one has mentioned Casoron in this six-year old thread. This pre-emergent is safe around shrubs (except hydrangea and a few others with green stems to ground level).

If your bed includes perennials or bulbs it unfortunately will kill them as well. It works by killing emerging stems, so will work well with this arum. Apply to dry soils and let rain or light irrigation activate it. Do so just before the arum sprouts in your area. Do not use in very light sandy soils.

Let me emphasize that this chemical should only be used with established woody plants to kill grasses, bulbs and broadleafed weeds. It should not be used in perennial or bulb beds or anywhere these or seeds will be planted for a year or more.

growershower: Speedzone is not made by Monsanto, so what is your point? You could spend a few seconds on a web search rather than showing everyone you are acting on assumptions.

I have what appears to be Arrow Arum, which came up after installing a drip system (it likes wetness). I erradicated it very simply. Using about a 1 1/2 to 2" piece of pipe foam, I then inserted a 1" strip of paper towel, folded and put inside the foam (which can be pulled open). After pricking a few holes with a safety pin or small nail into the plant about 2-3 inches above the ground, I sprayed the towel inside with ortho groundclear, then wrapped the foam around the base of the plant, just above the ground. I fastened it tightly with heavy plant wire. It appeared to kill not only the primary plant, but its offshoots also. I don't know if it works for all Arum species, but give it a try.

Hi, I'm also trying to eradicate this plant for a client who has it coming up everywhere in his quarter acre block. We have found that digging only stimulates the growth.
Have referred it to a local grower, who has advised me to first slash it, then apply double strength Roundup (available from Agricultural suppliers) to new growth and repeat every 9 days. They said it only needs three hours of dry weather to be effective. Hope this works & hope it helps you too!

I went out a bought SpeedZone at Coastal. It isn't any more effective than anything else I've tried: crossbow, roundup etc.

AND in the past week I've been to both Al's Garden Center in Sherwood and Dennis' 7 Dees on Powell and both have Arum Italicum for sale. Al's said they would notify the buyer and Dennis' 7 Dees worker said people still buy it (as if that's a legitimate excuse). I proceeded to ask her how to eradicate it and she said you had to make sure you don't ever disturb the soil (till it) and dig it up which begs the question: why are you selling it?

I think a key to eradicating arum is being methodical and persistent. As bad an invasive as this plant is (I HATE IT) and as indestructible as it appears, I have to remember it's a plant -- and has plant needs. One of its needs is foliage to feed the tubers and roots. Whether you use an herbicide or manually pull or cut the leaves(I find them easier to pull), if you consistently repeat it each time new leaves appear you'll eventually drain the tubers of food and energy.
I first started seeing it in my yard a few years ago and eventually traced it to seed from the neighbor's yard. I applied a broadleaf herbicide during active growth on maybe 3 or 4 occasions -- I was allowed to spray the neighbor's clumps as well. I use a 1-liter hand-held pump sprayer and get down close to the leaves so I can control the spray drift better. A couple times I did also dig them up (I use a good spading fork -- easier than a spade or shovel) and I spent several meditative hours separating bulblets from soil. As thorough as I thought I'd been, there were still some the next year. That's when I decided to just pull up and/or spray the leaves and stalks on a regular basis. That's worked pretty well.
Across the street is a woodland that's also been contaminated with arum -- that's going to be the next project. But for now I pull flower stalks when I see them (they're bright white and are easy to spot), and I check later for seed clusters in case I missed any flowers. I pull the stalks and make sure they go to the landfill and not to the city yard debris compost. I agree with the people who say that's one reason there seems to be more invasives spreading. I'm a landscape gardener, and during the past 15-20 years that city-wide yard debris composting has been going on I've seen a marked increase in invasives and plant pathogens in the landscape. I'm convinced it's from the yard debris that's brought from all over the region, composted (it doesn't get completely composted) and used for mulch. But that's another topic...
Good luck to everyone!

It is a tough plant...compounded with the problem that Roundup is most effective during periods of fast plant growth, when temps are around 70+ F. Unfortunately, Arum italicum is usually dormant then :)

Oh my goodness I am so happy to have found this thread! I bought a house in Portland last fall. This winter has revealed that the backyard is literally covered with Arum. I am not exaggerating - the only place the stuff isn't growing is the concrete patio. For the time being I have covered the entire yard with many layers of burlap but I'm ready to try a nuclear strategy.

Does anyone here have suggestions for dealing with a *huge* infested area? Dealing with each plant individually isn't realistic. SOS! And thanks!

I wish I was joking. The idea that anybody in North America could still be growing this stuff, it blows my mind. And how can people still find it attractive? Is poison ivy attractive? Is the soft twilight glow of radioactive waste attractive? We have to let our pain and hate inform our perspective. I hate Arum and it pains me, and my brain now thinks it's hideous. I find this both appropriate and convenient.

I wonder what outcomes people have had on control of this?
We have been working on a patch (hand dig and hoe) for several years and still they come up :-0
More recent advice has been to treat with eg. Brushoff (metsulphuron) and wetter, 1g to 15 lit. with a weed wiper or paint brush trying to avoid runoff because this may affect 'good' plants

1) Speedzone does, in fact, kill it, but it only really worked for me in the spring while the growth was still "fresh". I only tested this on the leaves so I don't know if it is effective on flower or seed stalks. I haven't gone through a full year yet so waiting til next spring to see if this herbicide reached the corms. It will definitely kill everything else too; smells like toxic petrochemical hell. I recommend a mask and eye protection.

2) For areas you don't want exposed to disgusting chemicals, mechanical suppression seems to be doing the job. As I posted before, I've got everything completely smothered in burlap (near veggie beds). It's working fairly well to control the arum...now we wait each other out. Vigilance!

Digging them up only spreads them. We have it in a contained area between the sidewalk and house. Twice I dug out the dirt at least a foot down and replaced it with new dirt, put down cardboard, landscape fabric, newspapers - they still came back. This last time I put down fabric and heavy river rocks. They were gone all summer but started sprouting on the edges this spring. I have sprayed the leaves with this formula in one gallon of water: 1.5 ounce each of Glyphosate (full strength Roundup) and a chickweed/clover killer (Bonide), one scoop of Miracle Grow and some dishwashing soap. Do not do this if it's windy out or the temperature is over 80F (it will kill other plants). I have done this twice in a week and the leaves look like they're chewed on. I may add more soap to make it stick better. Put a bucket with the end cut out over it before spraying if you have plants next to it.

If you have a small clump you can try digging it, but dig way down and the dirt will need to be bagged or thrown on a burning pile. I would mark the area to see if it comes back next year.

Another Portland, Oregon infestation here. I've been lurking in this thread and really appreciate reading other people's stories, especially updates on progress. I, too, asked for advice at Portland Nursery and basically got an eye-roll and "it sucks to be you" from their horticulturalist - this is much more helpful. I've (half) joked with neighbors that we need an Arum Support Group - for now, this is it for me! (along with neighbors).

Our story: We moved into our house in July/August 2013. Knew nothing about arum but a friend spotted it right away and warned us. We collected and threw away the berries but otherwise ignored it, being busy and not realizing just how bad it was until the following spring. Then we dug out a bunch of patches, throwing away the dirt (which filled our trash can and is SO heavy!), and patiently sifting for corms.

This spring, we're trying smothering in some parts, and I've been pulling up the greens. I just can't face digging it up yet, and like Jim6810, I hope it's still a plant, after all! My husband thinks it's better this year where we dug it last year and he promised to find me photos - I'll share if he does.

Right now I'm eying a large patch in a raspberry patch. The raspberries aren't well placed, so it won't be a tragedy if it all has to come out but it's such a large patch it makes me tired just looking at it ... ugh.

I may try Speedzone, especially where it's growing up in the lawn. And I promise to update! I sure do hope Houzz keeps this forum alive.